The objective of this application is to develop an activity-directed fractionation procedure designed to isolate from higher plants novel inhibitors of carcinogenesis. Based on previous experience in the isolation of novel antineoplastic agents from higher plants and using mammalial cell culture assays designed to detect the inhibitors of interest a variety of human foods shown to be correlated to reduced cancer incidence will be studied as follows: 1) Development of cell culture assays for detection of potential inhibitors of carcinogenesis. These assays will measure hydrocarbon metabolism, hydrocarbon-DNA interactions, and hydrocarbon-induced mutations in mammalian systems. 2) Acquisition of selected higher plants for initial screening leading to identification of a convenient assay to guide fractionation. 3) Bioassay-directed fractionation of plants including members of the Cruciferae, Umbelliferae, Leguminosae, and others which show reproducible activity in the bioassays in order to isolate pure, crystalline active components. 4) Determination of the complete structure and stereochemistry of crystalline actives using modern spectroscopic methods including nuclear magnetic resonance spectroscopy (NMR), mass spectrometry (MS), and X-ray crystallography. 5) Determine the mechanism of action of selected active components with high chemopreventive potential. 6) Development of analytical methods including HPLC, GCMS, and MSMS to detect these compounds at low levels in biological systems and other plants for purpose of dereplication, identification of other inhibitors, and other plant sources of inhibitors. The identification of these novel inhibitors will lead to a variety of agents with the potential of preventing human cancer, and in addition will provide a better understanding of the total inhibitor activity present in the plants, and their mechanism of action.